This is known as sampling, and is required during fixed wire testing to ensure an inspection has in fact taken place.
There are two main reasons we do this:
1. To confirm the accessory point is suitably fitted
2. To ensure there are no negative maintenance problems.
If a socket is to be found unsuitably fitted, I am often (for lack of a better word) attacked by the customer for making up problems.
This is because, logically, if a socket outlet is fitted, it will have been installed suitably and an appropriate certitificate would be issued.
The reality is that this is not always true. I don't make things up and I don't oversell problems. The fact is that many installations have been installed poorly and the systems that exist to prevent these issues are flawed.
Maintenance problems include loose connections, corrosion of steel back boxes and deteriation of wiring insulation.
